A method of correcting lag in an imaging pixel includes receiving a current frame pixel value and determining a current filter coefficient using the current frame pixel value. A pixel output is determined from a product of the current frame pixel value and current frame filter coefficient. The product of a first prior frame pixel value and corresponding first prior frame filter coefficient is added to the pixel output to generate a corrected pixel output to more closely indicates incident illumination on the imaging pixel during an integration period from which the current frame pixel value was obtained.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of correcting image lag in an imaging pixel, comprising: converting electromagnetic radiation in an infrared waveband into a first pixel value; receiving the first pixel value from a current frame; converting electromagnetic radiation in the infrared waveband into at least one second pixel value; receiving the at least one second pixel value from at least one of a prior frame and a subsequent frame; determining a first filter coefficient for the first pixel value; determining a second filter coefficient for the at least one second pixel value; calculating a pixel output by adding (a) a product of the first pixel value and the first filter coefficient to (b) a product of the at least one second pixel value and the corresponding second filter coefficient to compensate for image lag in the first pixel value; and displaying an image on a display device using the calculated pixel output.
2. The method as recited in claim 1 , wherein receiving the first pixel value from the current frame comprises receiving the first pixel value from a sensor and receiving a second pixel value of the at least one second pixel value from the prior frame includes receiving the second pixel value from a buffer.
3. The method as recited in claim 1 , wherein determining the second filter coefficients for the at least one second pixel value includes using the at least one second frame pixel value.
4. The method as recited in claim 1 , wherein receiving the at least one second pixel value comprises receiving a first prior frame pixel value from a prior frame, and at least one second prior frame pixel value from a different prior frame.
5. The method as recited in claim 4 , further comprising: determining a first prior frame filter coefficient using the first prior frame pixel value; and determining a second prior frame filter coefficient using the second prior frame pixel value, wherein calculating the pixel output further comprises adding a product of the first prior frame pixel value and the first prior frame filter coefficient and a product of the second prior frame pixel value and the second prior frame filter coefficient to the product of the first pixel value and the first filter coefficient.
6. The method as recited in claim 1 , further comprising buffering the first pixel value in a buffer.
7. The method as recited in claim 6 , wherein buffering the first pixel value includes replacing a second pixel value of the at least one second pixel value with the first pixel value.
8. The method as recited in claim 6 , wherein buffering the first pixel value includes removing a pixel value from a prior frame stored in the buffer.
9. The method as recited in claim 1 , wherein determining the first or second filter coefficients includes looking up the corresponding first or second filter coefficients in a lookup table stored in a memory.
10. The method as recited in claim 9 , wherein a lookup address for looking up the corresponding first or second filter coefficients includes the first pixel value and the a second pixel value of the at least one second pixel value from the prior frame.
11. The method as recited in claim 9 , wherein a lookup address for looking up the corresponding first or second filter coefficients includes the first pixel value and a second pixel value of the at least one second pixel value from the subsequent frame.
12. The method as recited in claim 1 , wherein receiving the first pixel value includes receiving the first pixel value at a filter coefficient module and a pixel output module.
13. The method as recited in claim 1 , further comprising: buffering the first pixel value and the at least one second pixel value on a readout interface circuit (ROIC); determining at least one of the first and second filter coefficients for the respective first pixel value and the at least one second pixel value from a lookup table stored on the ROIC; and calculating the pixel output is performed using a processor disposed on the ROIC.
14. The method as recited in claim 13 , wherein the buffered at least one second pixel value corresponds to at least one of a prior frame value received from a prior frame or a subsequent frame value received from a subsequent frame.
15. An imaging apparatus, comprising: a sensor comprising an array of imaging pixels; readout interface circuit (ROIC) disposed in communication with the sensor and having a processor and a buffer; and a memory having instructions recorded thereon that, when read by the processor, cause the processor to: convert electromagnetic radiation in an infrared waveband into a first pixel value; receive the first pixel value from an imaging pixel from a current frame; convert electromagnetic radiation in the infrared waveband into at least one second pixel value; receive the at least one second pixel value from the imaging pixel from at least one of a prior frame and a subsequent frame; determine a first filter coefficient for the first pixel value; determine a second filter coefficient for the corresponding at least one second pixel value; and calculate a pixel output of the imaging pixel for the current frame by adding (a) a product of the first pixel value and the first filter coefficient to (b) a product of the at least one second pixel value and the corresponding second filter coefficient to compensate for image lag in the first pixel value; and display an image on a display device using the calculated pixel output.
16. The apparatus as recited in claim 15 , wherein the buffer is co-located with the ROIC.
17. The apparatus as recited in claim 15 , wherein the memory is co-located with the ROIC.
18. The apparatus as recited in claim 15 , wherein the memory is remote from the ROTC.
19. The apparatus as recited in claim 15 , wherein the memory has a lookup table recorded on it with global pixel value filter coefficients addressed by pixel values corresponding to at least one prior frame, the global pixel value filter coefficients be nonspecific to a particular imaging pixel.
20. The apparatus as recited in claim 15 , wherein the memory has a lookup table recorded on it with global pixel value weights addressed by the first pixel value and the at least one second pixel value, the global pixel value weights being nonspecific to a particular imaging pixel.
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February 13, 2017
August 27, 2019
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